Types of occupancy monitoring sensors and their uses

Occupancy monitoring sensors can be a vital tool for anyone wanting to manage their buildings smartly and more efficiently. Like a crystal ball, they give you a clear and continuous picture of where, how and when a space is being used. Which means you can move away from responsive and reactive management into a future of informed decision making guided by the data.

This article looks at the most common types of sensors and the ways they can be used to help you see what’s happening in your buildings.

What are the different uses of occupancy sensor?

The data they provide can be used to help manage a wide range of functions within a workspace.

Space planning: You can monitor when and how desks, rooms and spaces are used over time and identify areas that are under-used or over-used. Helping you to make informed decisions about how you design your workspaces and grow or consolidate your real estate.

Resource management: Manage desk and meeting room booking more effectively with live, real-time information about which desks, rooms and breakout areas are being used. Helping improve availability accuracy, enable automatic check-in and detect no-shows.

Sustainability and wellbeing: Provide a better working environment for your staff and help save energy. Knowing which rooms are occupied, when and how many people are there, enables you to ensure heating, lighting and ventilation are just right for users. It also has the benefit of helping you to increase energy efficiency, as you can see empty areas and ensure lighting/heating/air-conditioning is switched off.

Cleaning and maintenance: COVID-19 brought about new challenges in terms of keeping areas uber clean. Sensors can indicate which resources have been used and at what capacity, so cleaning can be implemented.

Security: Knowing who’s where and when is key for security reasons. Sensors don’t replace alarm systems, but they can add an extra layer of security. In case of emergency, you know exactly where everyone is so you can alert them and let them know their nearest exit.

What are the different types of occupancy sensor?

Occupancy sensors usually use one of, or a combination of, the following types of technology. The information below should help you to choose the best smart occupancy sensor for your needs:

Passive infra-red (PIR): These sensors work by detecting heat from the human body. They receive thermal signals from their surrounding environment and are able to tell when these are interrupted by the presence of a human. PIR sensors come in varying forms, some as units which you stick to walls or ceiling, others that are placed under desks. They are usually unobtrusive, easy to install, low maintenance and a great cost-effective option.

Infrared time-of-flight (ToF) sensors: Emit an infrared light beam that reflects off a person and returns back to the sensor, the time taken to return gives an accurate distance calculation. The sensor uses these measurements to determine if the person is moving towards or away from the sensor, making it an effective entry/exit sensor.

Infrared array sensors: These sensors allow you to motionless or moving people by measuring the temperature emitted by a person as they move nearer or further from the sensor. As the distance from the sensor increases, the field of view expands but angular size appears smaller. As the proximity to the sensor narrows, the sensor can detect accurate temperature and shape. These types of sensor are GDPR and privacy-compliant solutions as no images or personal information is stored or transmitted.

Ultrasonic sensors: These send high frequency sound waves into an area to check for a reflected pattern. It recognises the steady state of the room, so if the reflected pattern is changing continuously it assumes there are people in the room. The sound waves are transmitted at about 40kHz, which is well above the level of human hearing.

Microwave sensors: Similar to ultrasonic sensors, these work by sending high frequency microwaves into an area and checking for a reflected pattern. The reflections change when a moving object enters the field of detection. Microwave sensors have a higher sensitivity and greater detection range than other types of sensor. It is important that their levels are set correctly when installed as the microwaves can penetrate through most building materials, which could lead to inaccurate readings.

People recognition cameras: These sensors read visible light from within the electromagnetic spectrum. They are able to identify outlines of faces or bodies to give an indication of the number of people within a space. They can give a more accurate picture of the usage of a room or a particular area than PIR sensors but are at the more expensive end of the spectrum, and there are potential privacy and security issues with the taking of video images.

“Occupancy monitoring and management is a critical part of effective workspace management. Using smart sensors combined with software you can see accurate real-time data. All working to create the big picture of exactly where, how and when.”

Jamie Burbudge, Product Manager

If you’d like to find out more about Pressac’s occupancy sensors, download our product brochure.

Editor’s note: This post was originally published in 2019 and has been updated for comprehensiveness February 3 2021.